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    <script>
        function isZhishu(n) {
            if (n <= 1) {
                return false;
            }
            for (let i = 2;i < n;i ++) {
                if (n % i == 0){
                    return false;
                } 
            }
            return true;
        }

        function sum(n) {
            let sum = 0;
            for (let i = 1;i <= n;i ++) {
                if (isZhishu(i)) {
                    sum += i;
                }
            }
            return sum;
        }

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